Variation in the Eastern Ocean.
Variation in the Eastern Ocean throughout the whole voyage to Goa and the
Moluccas is observed by the Portuguese; but they err greatly in many
things, following, as they do, the first observers who note down variations
in certain places with ill-adapted instruments, and by no means accurate
observations, or by some conjectures. As, for instance, in Brandöe Island,
they make the versorium deviate by 22 degrees to the north-west. For in no
region or place in the whole world, of not greater latitude, is there so
great a deviation; and, in reality, there the deviation is slight. Also
when they make out that at Mosambique the compass deviates by one rumbe to
the north-west, it is false; even though they use (as they are accustomed
to do) the Portuguese compass: for beyond all doubt on the shore of {182}
Mosambique the versorium inclines ¼ rumbe or even more to the south-west.
Very wrongly also beyond the æquator in the course to Goa they make the
little compass incline by 1½ rumbe to the west: whereas they should rather
have said that in the first part of the course the Portuguese compass
inclines by 1 rumbe: but that the true meridional compass inclines by ½
rumbe only. In order that the amount of variation in the Eastern Ocean may
be accurately settled in most places by our rules, there is needed a more
exact and truer survey of the southern land, which spreads out from the
south to the æquinoctial more than is commonly described on maps and
globes.
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